The following applications of common assignee contain some common disclosure as the present application:
U.S. patent application Ser. No. 09/565,685 entitled xe2x80x9cFlip Phone With PDA and Mode Selectionxe2x80x9d, filed May 5, 2000.
U.S. patent application Ser. No. 09/565,683 entitled xe2x80x9cTwo-Pin Connection for Portable Phone Keypadxe2x80x9d, filed May 5, 2000.
U.S. patent application Ser. No. 09/565,682 entitled xe2x80x9cA/D Converter Sharing for Keypad and Touch Panel of a Phonexe2x80x9d, filed May 5, 2000.
U.S. patent application Ser. No. 09/565,681 entitled xe2x80x9cSelecting Flip-Phone Operating Mode Using Flip Positionxe2x80x9d, filed May 5, 2000.
1. Field of the Invention
The present invention relates generally to the field of mobile communications. More particularly, the present invention relates to a system and method for detecting the open/close state of a telephone flip cover.
2. Related Art
Many mobile communications devices are now combining wireless phone technology with hand-held computer platforms that provide personal information management. Such hand-held computer devices are called personal digital assistants (PDAs). Combination mobile communications devices usually operate as two separate instruments, requiring separate liquid crystal displays (LCDs) and additional circuitry to read the separate input devices of the wireless phone and the PDA.
Matrix encoded keyboards and keypads are used extensively as input devices for computers and telephones. Such keyboards and keypads are usually mounted on a flex circuit and require multiple signal paths (that is, wires or conductive traces) to detect which key is pressed. For example, a 4 by 4 matrix keypad, which contains sixteen input keys, requires eight signal paths. When the keyboard or keypad is implemented on a flip cover, as may be the case with a wireless phone or PDA, multiple signal paths are routed to the body of the communications device through a hinge. The routing of multiple signal paths through a hinge causes the instrument to be less durable and may lead to the breakage of the hinge or the flex circuit if the instrument is constantly picked up by grasping the flip cover.
Many PDAs require a two-channel analog-to-digital converter (ADC) to read the touch panel display. When the PDA is combined with a wireless telephone that implements the keypad on a flip cover, additional circuitry usually includes an additional ADC to read the keypad on the flip cover and an additional LCD for the wireless telephone display.
What is needed is an efficient and cost effective way to integrate a PDA and wireless telephone with a flip cover that is lightweight, durable, and easy to operate. What is further needed is the integration of a PDA and wireless telephone that provides a user-friendly mechanism for changing the mode of operation of the device.
The present invention satisfies the above mentioned needs by providing a communications device that efficiently integrates a flip telephone with a PDA. The present invention operates as a single unit. According to a first embodiment of the present invention, the opening and closing of the flip cover activates a switch that changes the operating mode of the communications device. The communications device operates as a combination wireless telephone and personal digital assistant (PDA) when the flip cover is open. This is called the SMARTPHONE mode of operation. When the flip cover is closed, the communications device operates as a standard wireless telephone. This is known as the KEYPAD mode of operation.
According to a second embodiment of the present invention, the flip cover and hinge operate as a rotary switch to select the mode of operation of the communications device. Multiple contacts are located on the sides of the inner surface of the flip cover and a single contact is located on each side of the body of the communications device. Each contact located on the sides of the inner surface of the flip cover represents a different mode of operation for the communications device. As the flip cover rotates from the closed position to its final position as a stand, the mode of operation of the communications device changes as the contact from the body of the communications device connects with one of the contacts on the flip cover. Three modes of operation are presently implemented: the KEYPAD mode, the SMARTPHONE mode, and the SPEAKERPHONE mode.
The third embodiment of the present invention is a detection circuit that detects the open and closed state of the flip cover. The detection circuit includes a resistive network and an analog-to-digital converter (ADC). When the flip cover is in the closed position, the circuit detects a unique resistive value through a set of contacts. This voltage level is converted from an analog signal to a digital signal via the ADC for input into a microprocessor. When the flip cover is in the open position, the contacts are broken, thus, disabling the detection of the unique resistive value. The resulting voltage level is converted from an analog signal to a digital signal via the ADC for input into a microprocessor. Software, programmed within the microprocessor, enables the communications device to operate in the appropriate mode according to the detection of the open/close state of the flip cover.
Further features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawings in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.